FIG. 1 shows an example of a known turbine vane 10. The vane 10 includes an airfoil 12 bounded at each of its ends by a platform 14. The airfoil 12 and the platforms 14 are commonly formed as a single piece. The airfoil 12 is usually centrally located on each of the platforms 14 such that each end of the airfoil 12 is completely surrounded by the platform 14. Each platform 14 has opposite circumferential ends 16. The region 18 in which the airfoil 12 transitions into each platform 14 is typically configured as a fillet 20. The transition region 18 is an area that experiences high thermal stresses; however, the transition region 18 has historically proved to be a challenging area to adequately cool.
A plurality of vanes 10 are arranged in an annular array in the turbine section of the engine to form a row of vanes. When installed, the circumferential end 16 of each vane platform 14 abuts a circumferential end 16 of an adjacent vane platform 14, as shown in FIG. 2. The abutting circumferential ends 16 form a seam 22. The seam 22 is located midway between each pair of neighboring airfoils 12.
During engine operation, high pressure coolant can be supplied to the platforms 14. The seam 22 presents a potential leak path for the coolant. Despite efforts to seal the seam 22, a portion of the coolant inevitably leaks through the seam 22 and enters the turbine gas path. While providing some cooling benefit to the abutting portions of the platforms 14, such leakage flow through the seam 22 is not well controlled or optimized, resulting in excessive leakage in an area that requires relatively little cooling. Thus, there is a need for a turbine vane system that can make productive use of the leakage flow through the seam between adjacent vanes.